uio_hv_generic: Set event for all channels on the device

commit d062463edf1770427dc2d637df4088df4835aa47 upstream.

Hyper-V may offer a non latency sensitive device with subchannels without
monitor bit enabled. The decision is entirely on the Hyper-V host not
configurable within guest.

When a device has subchannels, also signal events for the subchannel
if its monitor bit is disabled.

This patch also removes the memory barrier when monitor bit is enabled
as it is not necessary. The memory barrier is only needed between
setting up interrupt mask and calling vmbus_set_event() when monitor
bit is disabled.

Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Link: https://lore.kernel.org/r/1741644721-20389-1-git-send-email-longli@linuxonhyperv.com
Fixes: b15b7d2a1b09 ("uio_hv_generic: Let userspace take care of interrupt mask")
Closes: https://bugs.debian.org/1120602
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
index 10d24f47c56426dce1247f09da116d1c51cd4a4d..0d7ebf7b35e1a078685ad14e2cf2e98ea0519335 100644 (file)
--- a/drivers/uio/uio_hv_generic.c
+++ b/drivers/uio/uio_hv_generic.c
@@ -80,9 +80,15 @@ hv_uio_irqcontrol(struct uio_info *info, s32 irq_state)
 {
        struct hv_uio_private_data *pdata = info->priv;
        struct hv_device *dev = pdata->device;
+       struct vmbus_channel *primary, *sc;
 
-       dev->channel->inbound.ring_buffer->interrupt_mask = !irq_state;
-       virt_mb();
+       primary = dev->channel;
+       primary->inbound.ring_buffer->interrupt_mask = !irq_state;
+
+       mutex_lock(&vmbus_connection.channel_mutex);
+       list_for_each_entry(sc, &primary->sc_list, sc_list)
+               sc->inbound.ring_buffer->interrupt_mask = !irq_state;
+       mutex_unlock(&vmbus_connection.channel_mutex);
 
        return 0;
 }
@@ -93,11 +99,18 @@ hv_uio_irqcontrol(struct uio_info *info, s32 irq_state)
 static void hv_uio_channel_cb(void *context)
 {
        struct vmbus_channel *chan = context;
-       struct hv_device *hv_dev = chan->device_obj;
-       struct hv_uio_private_data *pdata = hv_get_drvdata(hv_dev);
+       struct hv_device *hv_dev;
+       struct hv_uio_private_data *pdata;
 
        virt_mb();
 
+       /*
+        * The callback may come from a subchannel, in which case look
+        * for the hv device in the primary channel
+        */
+       hv_dev = chan->primary_channel ?
+                chan->primary_channel->device_obj : chan->device_obj;
+       pdata = hv_get_drvdata(hv_dev);
        uio_event_notify(&pdata->info);
 }